Most adult riders use 4.75-inch stirrups. 2. Choose the Right Type for Your Riding
The Ultimate Guide to Buying Stirrups: Comfort, Safety, and Performance what stirrups to buy
Your stirrups should be approximately 1 inch (2.5 cm) wider than your boot. This leaves about a half-inch (or one finger’s width) of clearance on both sides. Most adult riders use 4